Pendragon was one of seven proposed spin-offs for Gargoyles, for which the episode "Pendragon" was a back-door pilot.
Pendragon was initially pitched verbally, sparking some interest. 
In 2007, Greg Weisman rambled how he had tentative plans to release a Pendragon comic mini-series with Slave Labor Graphics following the initial spin-off run of Gargoyles: Bad Guys - Redemption.  By 2008, he had hoped to write it following a potential Gargoyles: The Dark Ages mini-series. 
In the series, King Arthur and Sir Griff embark on their quest for Merlin, visiting such places as Tintagel, Stonehenge, and even the South Pole.  Along the way, they gain the Lady Blanchefleur, Peredur's wife, for a companion.  Arthur and his companions would have engaged in a number of clashes with the Illuminati (no doubt connected to Peredur's leadership of the Illuminati). They would also have encountered the Stone of Destiny again, in an episode reflecting its real-life return to Scotland in 1996. (The Stone of Destiny story appeared in issues #7 through #9 of the Gargoyles comic book series, making up the first half of Gargoyles: Clan-Building, Volume Two. In "Rock and Roll", Arthur tells Macbeth and Hudson that he and Griff had searched the obvious places for Merlin, so presumably their visits to Tintagel and Stonehenge have already taken place. The Illuminati only become aware of Arthur's awakening at the end of "Rock of Ages", when the Stone informs Peredur of this; Peredur responds by alerting the upper echelon members of the Illuminati to this unexpected development.)
Merlin's possessions that were found in 1995 by archaeologists Lydia Duane and Arthur Morwood-Smyth, including the Scrolls of Merlin, would have been furthered explored.  Arthur and his companions would (presumably by the end of the first season) eventually find Merlin in his Crystal Cave, and somehow released him.  Afterwards, they would embark upon a fresh quest, for the Holy Grail. It is also possibile that the Questing Beast might make an appearance.  At some point, presumably, the issue would have arisen about Arthur's having been awakened early, well ahead of schedule for "Britain's greatest hour of need" that was supposed to be the occasion for his return from Avalon, and also the issue of what his ultimate goal in the modern world would have been. (Further evidence now reveals that Arthur will ultimately found his new headquarters in Antarctica, as New Camelot.)
As Arthur and Sir Griff are largely baseless before the founding of New Camelot (though they are always welcome to stay with the London Clan), this and transportation to and from their various quests would have been issues to be dealt within the series. 
In 2005, Greg Weisman hinted that even Arthur's ultimate death (which would not come for some time) wouldn't necessarily end the series, having at least one idea to take the show "beyond Arthur". 
In 2022, on the Voices from the Eyrie podcast, Greg Weisman also teased that the series would also feature scenes with gargoyles "set during Arthurian times" and how the gargoyles "interacted with King Arthur and the knights of the Round Table."